Method of x-ray fluorescence analysis of materials containing an interfering element

Claim 2

In a method of analysis of a mineral mixture containing a wanted element, an interfering element and a base rock, wherein the mixture is subjected to ionizing radiation of an energy sufficient to excite X-ray fluorescence in the wanted element and the intensity of the combined backscattered X-ray and fluorescent X-radiation is measured: the improvement comprising the steps of, a. detecting the intensity Iw at the characteristic X-ray fluorescent energy Ew of the wanted element; b. separately detecting the intensity Ii at the characteristic X-ray fluorescent energy Ei of the interfering element; c. separately detecting the intensity Ib of backscattered Xradiation over an X-ray energy band intermediate between but excluding Ew and Ei; d. determining the ratios Ii/Ib and Iw/Ib; and e. comparing said ratios with a suitable calibration nomogram which plots the ratio Ii/Ib versus the ratio Iw/Ib to determine the concentration of the wanted element.

Claim 3

A method according to claim 1, wherein the source of ionizing radiation is a radioisotope and the measurements are made using a pair of balanced filters for each determination.

Claim 4

A method according to claim 2, wherein the pair of balanced filters used iN determining the intensity of the radiation over said intermediate band comprises one filter from each of the other two pairs of balanced filters, whereby only four counts need to be made.

Claim 5

In a method of analysis of a mineral mixture containing a wanted element, first and second interfering elements and a base rock wherein the mixture is subjected to ionizing radiation of an energy sufficient to excite X-ray fluorescence in the wanted element and the intensity of the combined backscattered X-ray and fluorescent X-radiation is measured: the improvement comprising the steps of, a. detecting the intensity Iw at the characteristic X-ray fluorescent energy Ew of the wanted element; b. separately detecting the intensity Ii at the characteristic fluorescent energy Ei of the first interfering element; c. separately detecting the intensity Ii at the characteristic fluorescent energy Ei of the second interfering element; d. separately detecting the intensity Ib of backscattered X-radiation over an X-ray energy band intermediate between but excluding Ew, Ei and Ei ; e. determining the ratios Ii /Ib, Ii /Ib and Iw/Ib; and f. comparing said ratios with a suitable three-dimensional calibration nomogram which plots the ratio Ii /Ib versus the ratio Ii/Ib versus the ratio Iw/Ib to determine the concentration of the wanted element.

Claim 6

In a method of analysis of a mineral mixture containing a wanted element, first and second interfering elements and a base rock wherein the mixture is subjected to ionizing radiation of an energy sufficient to excite X-ray fluorescence in the wanted element and the intensity of the combined backscattered X-ray and fluorescent X-radiation is measured: the improvement comprising the steps of, a. detecting the intensity Iw at the characteristic X-ray fluorescent energy Ew of the wanted element; b. separately detecting the intensity Ii at the characteristic fluorescent energy Ei of the first interfering element; c. separately detecting the intensity Ii at the characteristic fluorescent energy Ei of the second interfering element; d. separately detecting the intensity Ib of backscattered X-radiation over an X-ray energy band intermediate between but excluding Ew, Ei and Ei ; e. determining the ratios Ii /Ib, Ii /Ib and Iw/Ib; and f. comparing said ratios with a suitable three-dimensional calibration nomogram which plots the ratio Ii /Ib versus the ratio Ii/Ib versus the ratio Iw/Ib to determine the concentration of the wanted element.